Add info on sending underscored JSON for create/update operations

In 0.13 the REST Adapter would send underscored JSON for create/update
requests.  Beginning in Beta 1 the REST Adapter sends camelized JSON.

This PR updates TRANSISTION.md to show how to get back to underscores.
Ability to serialize null belongsTo
Infer type of a hasMany relationship from the relationship's key
Make type-inferring of hasMany relationship work with options
Ensure license and version are in all builds.
Merge pull request #1277 from rjackson/add_version_info_to_prod_builds

Ensure license and version are in all builds.
Merge pull request #1258 from balinterdi/intuit-has-many-type

Infer type of hasMany relationship from the key
Merge pull request #1272 from teddyzeenny/serialize-belongsto

Ability to serialize null belongsTo
Add serializePolymorphicType hook and move it from
the JSONSerializer to the RESTSerializer
Document serializeIntoHash method
Add ActiveModelAdapter and Serializer
Document the AMS adapter
Move everything to a package
Added a failing test for multiple find() calls for the same id
Update TRANSITION.md

Added some clarification around ActiveModelSerializer terminology.
Add metadataFor
Merge pull request #1286 from thomasboyt/metadataFor

Add metadataFor
Merge pull request #1206 from bradleypriest/ams

Basic DS.ActiveModelSerializer implementation
Add some basic docs
Override normalizeRelationships to extract polymorphic type correctly